论文部分内容阅读
故障1 现象:M1724打印机开机后,能执行初始化工作,字车返回到起始位置,并能自检打印,但和主机相联时,打印丢字符。分析:由M1724打印机的逻辑原理图得知,打印机丢字符主要与忙(busy)信号有关。当打印机和主机联机打印时,主机通过接口向打印机发送要打印的数据。当打印机接收主机送来的数据时,若先进先出缓存器已满,则由74LS05的脚6向主机发出一个忙信号(高电平有效),表示打印机不能再接收数据。这样使主机处于等待状态,直到忙信号变低后,打印机方能继续接收主机送来的数据。若忙信号一直不为高电平,
Fault 1 phenomenon: M1724 printer boot, the initialization can be performed, the car returns to the starting position, and can print self-test, but associated with the host, print lost characters. Analysis: According to the logic diagram of the M1724 printer, the printer lost characters mainly related to the busy signal. When the printer and the host are printing online, the host sends the data to be printed to the printer via the interface. When the printer receives data sent from the host computer, if the FIFO register is full, a busy signal (active high) is sent from the pin 6 of the 74LS05 to the host, indicating that the printer can no longer receive data. This makes the host in a wait state, until the busy signal goes low, the printer can continue to receive data sent by the host. If the busy signal is not high,